Apple tree disease - please help!

Sorry, not sure what this is. Is the tree in a pot or the ground?

The tree is in the ground in a sunny site (clay but mixed in with lots of soil, manure and other soil improver when planted).

It could just be a very bad example of Scab in which case spraying with a fungicide might help. But, it also could be Apple mosaic virus which has no cure and you should seek advice from the person who sold it to you.

Это нехватка питания. Проявляется на глине в холодную весну и начало лета. Обработайте калемагнезией 20 гр. на 10 л.

Translation of above
This is a shortage of food. It appears on clay in the cold spring and early summer. Treat with kalemagnesia.

Never heard of kalemagnesia and never seen lack of food producing that effect on Apple trees before either.

If you had the following conditions.
1. The tree on the clone rootstock (M9, MM106, 54-118, etc.).
2. Clayey, sour crocs.
3. Cold spring and early summer.
4. Strong wind and waterlogging.
5. The soil is depleted by grass mowing or the cultivation of other crops without the application of fertilizers.
Then it is nutrition dysfunction. Even better, do soil analysis.

This is a very old thread. I am not sure that the person who asked is still an active member.